1. Field of the Invention
The invention relates to a wire drawing machine having a watching system of the wire diameter at a watched location.
2. Description of the Related Art
A wire drawing machine comprises a number of passes, from one to ten or even more, the one downstream after the other, and in each pass the wire diameter is reduced. In order to watch over the good operation of the machine, it is desirable to watch the diameter at one or more specific locations, e.g. at the exit of one or more of the passes. Due to the wear of the drawing-die indeed, the wire diameter at the exit of such pass becomes greater and greater, and after a certain time, when the diameter exceeds the tolerance limit, the die has to be replaced. It is however not easy to continuously measure the diameter of a wire traveling at a speed of 2 to 12 m/sec, because mechanical systems are disturbed by the movement of the wire and optical systems are disturbed by dust or other pollution, or are very expensive. For that reason, in practice, the operator of the machine simply measures the wire manually when the machine is stopped for whatever reason, and when the diameter appears to have somewhat approached the limit, he replaces the drawing-die as a precautionary measure. In this way, die consumption is higher than it should be. That is, if the operator were able to continuously watch the wire diameter during the operation of the machine, he would only replace the die when it is really necessary.
Although the need of watching the wire diameter at the exit of a drawing pass has been explained hereabove, and although the explanations hereinafter will refer to watching the diameter at the exit of the drawing pass, it is clear that the invention is not limited to a watched location at the exit side of a drawing pass, but can also be usable at an entrance side thereof.